The internal illumination of refrigerators and freezers is known to be provided by means of a light bulb mounted within a light-bulb holder fixed inside the household appliance and activated by means of a lever switch controlled, in turn, by means of the opening/closing of the refrigerator or freezer door. This switch, which is connected, on one side, to the household appliance electrical power cable and, on the other side, to the light-bulb holder, is normally maintained in its OPEN position by means of the bulk of the door, in the closed position, against which a switch lever is biased by means of a spring. When the door is opened by the user, means of a spring is no longer restrained by means of the bulk of the door and therefore biases the switch to its closed position, thus illuminating the light bulb. When the door is being closed, the lever is moved against the biasing force of the spring as soon as it is contacted by means of the door, thus extinguishing the light.
Another electrical device present within a refrigerator and that must be supplied by the aforenoted electrical power and installed near the light-bulb holder, so that the user is able to read it, is the thermostat for regulating the temperature within the refrigerator, which in current household appliances is supported and powered separately from the lamp-holder. It is obvious that it requires an extremely complex design to install and power the light-bulb holder separately from the other electrical accessories, such as the thermostat and the switch, present within the household appliance. To these circumstances must be added the fact that the various thermostat models currently used require widely different power connections, thus making it necessary to provide assembly bases for the different thermostats, according to their type. This drawback becomes even more difficult to resolve if the designer wished to use the light-bulb holder as a base for the thermostat, as it would be necessary to provide numerous design variants of the same model in accordance with the type of thermostat used, with consequent high manufacturing costs due to the lack of large-scale economy, assembly and storage complications.